The present disclosure relates to a technique to perform a brake control that decelerates or stops a motor by generating a braking force on the motor.
An electric power tool disclosed in Japanese Unexamined Patent Application Publication No. 3-74194 performs so-called short-circuit braking in which a motor control device generates a braking force on a motor by forming a short circuit between terminals of the motor through a bridge circuit to decelerate or stop the motor.
This control device is configured to control driving of a three-phase brushless motor and includes a bridge circuit having a total of six switching elements, each of which is provided between a corresponding one of terminals of the three-phase brushless motor and a positive electrode side or a negative electrode side of a direct-current power source.
From among the switching elements, switching elements on the negative electrode side (so-called low-side switches) are turned into an on-state and switching elements on the positive electrode side (so-called high-side switches) are turned into an off-state when the control device generates a braking force on the motor.
This control device can thus control the driving and braking of the motor only by switching the on/off-state of the switching elements in the bridge circuit.